The present invention concerns a set of triple clamps (also sometimes said T-pieces due to their particular form) in a front suspension system of a motorcycle, said assembly comprising a top triple clamp and bottom triple clamp designed to provide a pivoting connection of the front suspension system of the motorcycle with the frame of said motorcycle, said assembly also comprising a fixing system for receiving the handlebars of said motorcycle and fixing them to the top triple clamp.
FIG. 1 shows a motorcycle that conventionally consists essentially of a frame 1 on which there are mounted an engine 2, a rear wheel 3 by means of a rear suspension system 4 and a front wheel 5 by means of a front suspension system 6, itself consisting here, solely by way of example, of an inverted telescopic fork.
FIG. 2 shows a fork of a motorcycle that is of the inverted telescopic type. As will be understood hereinafter, the present invention could apply to any type of motorcycle fork.
The fork shown in FIG. 2 comprises two sheaths 10 and 11 in which two plunger tubes 12 and 13 can respectively slide. At the end of these plunger tubes 12 and 13, means are provided for mounting the front wheel of the motorcycle. Only the axis xx′ of this wheel is shown in FIG. 2.
A motorcycle front fork as has just been described consists of a damper system that comprises firstly an elastic element, such as a spring or a pressurised gas the behaviour of which is such that pressing the plunger tubes 12 and 13 into the sheaths 10 and 11 is approximately proportional to the amplitude of the force that is exerted on the fork, and, secondly a hydraulic element the behaviour of which is such that the pressing of the plunger tubes 12 and 13 into the sheaths 10 and 11 takes place progressively.
Thus the greater the amplitude of an impact, the more the plunger tubes 12 and 13 will be pressed into the sheaths 10 and 11. Nevertheless, the more rapid the impact, the slower will be this pressing in.
It should be noted that in general the range of travel of such a fork is around 100 mm to 300 mm.
In the remainder of the description, the term damper system will be given solely to any system that has this double behaviour: an elastic behaviour and a dynamic behaviour.
The front suspension system 6 (more precisely here in the particular embodiment considered, the sheaths 10 and 11) is fixed to a set of triple clamps, the subject of the present invention, consisting of two triple clamps, one bottom 20 and the other top 21, which provide the connection of the two sheaths 10 and 11 so that they are parallel to each other. Each triple clamp 20 and 21 is mounted on a shaft so that the whole of the fork can pivot on a substantially vertical forwardly inclined axis yy′ (only this axis yy′ is shown in FIG. 2) with respect to the steering column 30 of the motorcycle frame 1. Thus a set of triple clamps provides a pivoting connection of the front suspension system 6 of the motorcycle with the frame of said motorcycle.
On the top triple clamp 21 the handlebars 40 of the motorcycle are mounted, generally by means of bridge plates or pairs of bottom 41a and top 41b bridges. Conventionally, a bridge plate or a pair of bridges 41a is fixed to the top triple clamp 21 and the handlebars 40 are clamped against it by means of another bridge plate or pair of bridges 41b that fits on top of it and is fixed to the plate or bottom pair 41a. In general terms, the bridge plates or bridges constitute a fixing system for receiving the handlebars 40 of said motorcycle and fixing them to the top triple clamp 21.
It will be noted that, in FIG. 2, some of the elements shown are also present in FIG. 1 under the same references.
Handlebar fixing systems are known that also comprise elastic means placed between the bridge plate to which the handlebars of said motorcycle are fixed and the top triple clamp of the set of triple clamps. Reference can be made to the document U.S. Pat. No. 6,322,625. Such means improve the comfort of the rider of the motorcycle compared with a situation where such means are absent. Nevertheless, this improvement in comfort takes place to the detriment of the precision of riding, in particular the steering of the motorcycle, especially on uneven ground and at relatively high speed. This is because the elastic effect acts in all directions, both vertically and laterally. There also results from the presence of these means an effect of rocking of the fork about its pivot axis, known in the language of motorcycle experts as “handlebar shake”, which may prove dangerous on uneven ground.